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Frequent vs. infrequent irrigation are two common irrigation practices. This field study was conducted on 'Providence' creeping bentgrass (Agrostis stolonifera L.) grown on a sand-based rootzone and maintained as a putting green. The objectives of this study were to measure several creeping bentgrass performance and physiological factors as influenced by light and frequent (LF) vs. deep and infrequent (DI) irrigation. The LF plots were irrigated daily to moisten the upper 4 to 6 cm of soil, while DI plots were irrigated at leaf wilt to wet soil to a depth of [greater than or equal to] 24 cm. The LF-irrigated creeping bentgrass exhibited very good color and quality throughout most of 2006 and 2007, whereas DI-irrigated bentgrass exhibited acceptable quality in 2007 but not in 2006. The DI-irrigated bentgrass had lower chlorophyll levels in leaf and sheath tissue in 2006, but developed better color and quality and had higher chlorophyll levels in late summer of 2007 vs. LF-irrigated bentgrass. Creeping bentgrass subjected to DI irrigation developed a less thick thatch--mat layer that contained less organic matter than that found in LF-irrigated plots. Twice the amount of water was applied to the LF-vs. the DI-irrigated plots.

Coring is a common cultural practice used on golf courses. The reported effects of coring alone on thatch--mat accumulation have been mixed. The objectives of this field study were to examine the effects of spring and summer coring on thatch-mat thickness and organic matter accumulation in creeping bentgrass (Agrostis stolonifera L.). Turfgrass color and quality and chlorophyll content were also monitored. The study site was 'Providence' creeping bentgrass grown on a sand-based rootzone maintained as a putting green. Three coring regimes were assessed as follows: spring-only coring (1.27-cm-diam. tines), spring plus three summer corings (0.64-cm-diam. tines), and a noncored control. At the end of the second year, spring-only and spring-plus-summer cored plots had developed a 66 and 89%, respectively, thicker thatch-mat layer compared with noncored bentgrass. The total organic matter content (weight loss-on-ignition) in thatch--mat layers, however, generally was similar among all three regimes in both years. This indicated that the organic matter was diluted by inclusion of sand from topdressing or reincorporation of cores. Thus, organic matter concentration (i.e., gravimetric organic: dry weight of the cores) in the thatch--mat layer was much lower in plots of both coring regimes vs. noncored plots. Both spring-only and especially spring-plus-summer coring caused substantial reductions in turf quality for a 2-wk period. Spring-plus-summer coring resulted in increased chlorophyll levels as well as improved turf color and quality in late summer.

Light and frequent (LF) and deep and infrequent (DI) irrigation are two common practices for golf course managers. Few studies have compared the effects of these two opposing irrigation practices on summer root performance in creeping bentgrass (Agrostis stolonifera L.). The objectives of this field study were to quantify summer root development and longevity in response to LF vs. DI irrigation in 'Providence' creeping bentgrass grown on a sand-based rootzone. The LF plots were irrigated daily to moisten the upper 4 to 6 cm of soil, whereas DI plots were irrigated at leaf wilt to wet soil to a depth [greater than or equal to] 24 cm. Root measurements were obtained using the minirhizotron imaging technique and included total root count, total root length (TRL), total root surface area (TRSA), and average root diameter. When averaged over the entire 0-to 24-cm rootzone depth, DI-irrigated creeping bentgrass produced a greater number of roots, longer root lengths, and a larger root surface area than LF-irrigated turf. Average root diameters were smaller in DI-irrigated creeping bentgrass in the summer of 2007. Compared with data collected in 2006, the 2-yr-old turf had 55 and 32% fewer roots in LF-and DI-irrigated bentgrass by September 2007, respectively. There were similar reductions in TRL and TRSA between years in both irrigation regimes. Deep and infrequent irrigation stimulated root growth throughout the 0-to 24-cm rootzone in May and June and promoted root longevity in summer.

Annual bluegrass (Poa annua L.; ABG) can be a major weed problem in golf course turf, Research-based information on the seasonal emergence patterns of ABG is limited. The objectives of this four-year field study were (i) to determine seasonal ABG emergence patterns in Maryland, (ii) to determine peak period(s) of ABG emergence, and (iii) to determine the date and estimated percentage of seedlings emerged when the rate of emergence declines. Annual bluegrass seedlings were found to emerge between August and May in two Maryland golf course roughs. A majority (50-70%) of seedling emergence occurred between late September and mid-October, and peak germination generally was observed in early October. The linear increase in ABG seedling emergence generally ended by early November; however, 24% of all seedlings emerged between November and May. No major ABG emergence cycles were observed during the spring in any year. Mean daily temperatures generally were [less than or equal to] 20[degrees]C during peak ABG emergence periods, and germination was stimulated by precipitation. Since the genetic diversity of ABG is well known, these findings may only be applicable to Maryland and regions with similar environmental conditions.

Creeping bentgrass [Agrostis stolonifera L. var. palustris (Huds.) Farw.] and perennial ryegrass (Lolium perenne L.) are commonly grown fairway grasses that are susceptible to dollar spot (Sclerotinia homoeocarpa F. T. Bennett; DS) and gray leaf spot [Pyricularia grisea (Cooke) Sacc; GLS.] diseases, respectively. This field study assessed the influence of two irrigation regimes (light and frequent nighttime versus deep and infrequent morning irrigation) and six chemical treatments including: chlorothalonil (tetrachloroisophthalonitrile), paclobutrazol [(2RS,3RS)-1-(4-chlorophenyl)-4,4-dimethyl-2-(1H-1,2,4-triazol-1-yl) pentan-3-ol; PB], wetting agent (polymeric polyoxyalkylene 95% oxoalkonyl hydroxyl polyoxlalkane diyl 5%; WA), chlorothalonil + PB, chlorothalonil + WA and chlorothalonil + PB + WA on DS and GLS severity over a 3-yr period. Dollar spot was more severe in late summer in creeping bentgrass that received deep and infrequent versus light and frequent irrigation in 2002 and 2004 and disease severity was negatively correlated with volumetric soil moisture (r = -0.77 to -0.96). Soil moisture levels above 0.25 [cm.sup.3] [cm.sup.-3] were associated with an improved ability of chlorothalonil, PB, and WA to suppress DS, but they had no effect on GLS. In 2002, GLS rapidly and severely damaged even fungicide-treated plots, and there was no irrigation effect. In 2004, gray leaf spot was more severe in light and frequent nighttime irrigated blocks versus deep and infrequent morning irrigated blocks. Chlorothalonil (8.0 kg a.i. [ha.sup.-1]) provided effective GLS control when applied on an 8-d interval in 2004 but only in infrequently irrigated blocks where disease pressure was less.

There is increasing interest in the use of bio-organic nitrogen (N) sources to suppress turfgrass diseases. The objectives of this field study were to evaluate nine N-sources for their effects on dollar spot (caused by Sclerotinia homoeocarpa F. T. Bennett) severity; to elucidate the relationship among N-sources, tissue N, soil microbial activity, and the severity of dollar spot; and to evaluate N-source effects on thatch and soil organic matter levels, and plant parasitic nematodes. Nitrogen sources included urea, sulfur-coated urea (SCU), Milorganite (Milwaukee Metropolitan Sewerage District, Milwaukee, WI), Sustane Medium (Sustane Corporation, Chaska, MN), Earthgro 1881 Select (Earthgro Inc., Lebanon, CT), Earthgro Dehydrated Manure, Ringer Lawn Restore (Ringer LR, Ringer Corporation, Minneapolis, MN), Com-Pro (Blue Plains Sanitation Commission, Silver Spring, MD), and Scotts All Natural Turf Builder (Scotts ANTB, Scotts Company, Marysville, OH). The N was applied annually at a rate of 200 kg N [ha.sup.-1] [yr.sup.-1] between 1994 and 2000 to a stand of fairway height `Southshore' creeping bentgrass (Agrostis stolonifera L.). Data were collected between 1998 and 2000. Ringer Lawn Restore (all 3 yr) and urea (1999 and 2000) delayed dollar spot to within an acceptable threshold from May to early or mid-June, when disease pressure was low to moderately severe. Com-Pro (all 3 yr), however, enhanced dollar spot. No N-source reduced dollar spot when data were averaged over-the-season. No N-source was consistently associated with higher levels of soil microbial activity. There was a weak negative correlation between soil microbial activity and dollar spot on one date in 2000, when disease pressure was low. When disease pressure was moderately severe, there was a strong negative correlation between the amount of foliar N and dollar spot severity in June 1999, but no correlation was found in 2000. Only Sustane Medium-treated plots had higher organic matter levels in the upper 2.5 cm of soil on all rating dates, but there was no increase in soil organic matter in the 2.6 to 5.0 cm soil zone with any N-source., THERE IS INCREASING INTEREST in the use of natural or bio-organic nitrogen (N) sources and soil amendments for use on turfgrasses. Several natural fertilizers are good N sources and their [...]

Brown patch (Rhizoctonia solani Kuhn) is a destructive disease of turfgrasses, but more is known regarding its management with fungicides than by cultural practices. This field study was conducted to determine the influence of mowing height and nitrogen (N) source on brown patch severity. 'Caravelle' perennial ryegrass (Lolium perenne L.) was subjected to two mowing heights (1.7 versus 4.5 cm) and fertilized with one of eight N sources at rates of 196 kg N [ha.sup.-1] [yr.sup.-1] from 1991 to 1993. Plots were split with one-half receiving iprodione [3-(3,5-dichlorophenyl)-N-(1-methylethyl)-2,4-dioxo-(1-imidazolid ine-carboxamide)] (3.1 kg ai [ha.sup.-1] applied on a 21-d interval) and the other half receiving none. The complete combination of treatments were assessed at Silver Spring, MD, and in a second trial the N sources alone were assessed on a perennial ryegrass fairway in Pikesville, MD. In non-fungicide-treated plots, turf maintained at 1.7 cm was blighted more by brown patch in 1991, but in 1992 and 1993 blighting was more severe in plots mowed to a height of 4.5 cm. Blighting was reduced by iprodione at both mowing heights, and summer turfgrass quality was improved in all plots receiving N plus iprodione. Ammonium sulfate in 1991 and Sustane and Ringer Lawn Restore-treated turf in 1992 were associated with less blighting among non-fungicide-treated plots at Silver Spring. Non-fungicide-treated Sustane and Ringer Lawn Restore plots had blight levels equivalent to most fungicide-treated plots in 1992, but the quality of non-fungicide-treated plots was inferior. No N source had any significant effect on brown patch at Pikesville in any year. No single N source combined with iprodione was consistently associated with improved disease suppression or turf quality. There was no apparent relationship between brown patch severity and soil pH or crown tissue carbohydrates. Plant parasitic nematode population densities were not influenced by any N source.

Brown patch (Rhizoctonia solani Kuhn) is a common and destructive disease of turfgrasses, but little information is available regarding its management by cultural practices. This 2-yr field study assessed the influence of irrigation, and N source alone or in combination with P and K on brown patch severity. Perennial ryegrass (Lolium perenne L. cv. 'Caravelle') was subjected to either morning or evening irrigation. Sodium nitrate, a quickly available non-soil reacting N source, was compared with sulfur-coated urea (SCU), a slowly available soil acidifying N source. Fertilizer treatments were applied three (May-September-October) and six (March-May-June-September-October-November) times annually, representing lower and higher N application rates, respectively. Forty-nine kilograms N per hectare were applied on each date for a total of 147 and 294 kg N [ha.sup.-1] [yr.sup.-1]. Plots were split with one-half treated with iprodione [3-(3,5-dichlorophenyl)-IRN-(1-methylethyl)-2,4-dioxo-(1-imidazol idine-carboxamide)] (3.1 kg ai [ha.sup.-1]) on an extended 21-d interval. In non-fungicide-treated plots, brown patch severity was consistently reduced with morning irrigation when compared with evening-irrigation. Non-fungicide-treated plots fertilized with SCU generally had lower blight levels than NaN[O.sub.3]-treated plots, regardless of N rate. In the second year, brown patch was more severe in plots treated with the high N rate, and P (72 kg [ha.sup.-1] [yr.sup.-1]) and K (150 kg [ha.sup.-1] [yr.sup.-1]) reduced blight for both N-sources in non-fungicide-treated plots. Sulfur-coated urea applied at the high N rate plus P and K resulted in blight levels equivalent to or less than low N. Fungicide-treated plots receiving the high rate of N from SCU plus P and K had the highest summer quality in both years. While low soil pH was weekly correlated (r = 0.352) with less blight, the slow N release characteristics of SCU were probably a more important factor in disease reduction than soil acidification. While brown patch severity was reduced by morning irrigation, SCU + P + K, and iprodione, an excellent level of summer turfgrass quality was not achieved using the extended fungicide application interval.

Frequent vs. infrequent irrigation are two common irrigation practices. This field study was conducted on 'Providence' creeping bentgrass (Agrostis stolonifera L.) grown on a sand-based rootzone and maintained as a putting green. The objectives of this study were to measure several creeping bentgrass performance and physiological factors as influenced by light and frequent (LF) vs. deep and infrequent (DI) irrigation. The LF plots were irrigated daily to moisten the upper 4 to 6 cm of soil, while DI plots were irrigated at leaf wilt to wet soil to a depth of ≥24 cm. The LF-irrigated creeping bentgrass exhibited very good color and quality throughout most of 2006 and 2007, whereas DI-irrigated bentgrass exhibited acceptable quality in 2007 but not in 2006. The DI-irrigated bentgrass had lower chlorophyll levels in leaf and sheath tissue in 2006, but developed better color and quality and had higher chlorophyll levels in late summer of 2007 vs. LF-irrigated bentgrass. Creeping bentgrass subjected to DI irrigation developed a less thick thatch-mat layer that contained less organic matter than that found in LF-irrigated plots. Twice the amount of water was applied to the LF- vs. the DI-irrigated plots. [ABSTRACT FROM AUTHOR]

Light and frequent (LF) and deep and infrequent (DI) irrigation are two common practices for golf course managers. Few studies have compared the effects of these two opposing irrigation practices on summer root performance in creeping bentgrass (Agrostis stolonifera L.). The objectives of this field study were to quantify summer root development and longevity in response to LF vs. DI irrigation in 'Providence' creeping bentgrass grown on a sand-based rootzone. The LF plots were irrigated daily to moisten the upper 4 to 6 cm of soil, whereas DI plots were irrigated at leaf wilt to wet soil to a depth ≥24 cm. Root measurements were obtained using the minirhizotron imaging technique and included total root count, total root length (TRL), total root surface area (TRSA), and average root diameter. When averaged over the entire 0- to 24-cm rootzone depth, DI-irrigated creeping bentgrass produced a greater number of roots, longer root lengths, and a larger root surface area than LF-irrigated turf. Average root diameters were smaller in DI-irrigated creeping bentgrass in the summer of 2007. Compared with data collected in 2006, the 2-yr-old turf had 55 and 32% fewer roots in LF- and DI-irrigated bentgrass by September 2007, respectively. There were similar reductions in TRL and TRSA between years in both irrigation regimes. Deep and infrequent irrigation stimulated root growth throughout the 0- to 24-cm rootzone in May and June and promoted root longevity in summer. [ABSTRACT FROM AUTHOR]

Coring is a common cultural practice used on golf courses. The reported effects of coring alone on thatch-mat accumulation have been mixed. The objectives of this field study were to examine the effects of spring and summer coring on thatch- mat thickness and organic matter accumulation in creeping bentgrass (Agrostis stolonifera L.). Turfgrass color and quality and chlorophyll content were also monitored. The study site was 'Providence' creeping bentgrass grown on a sand-based rootzone maintained as a putting green. Three coring regimes were assessed as follows: spring-only coring (1.27-cm-diam. tines), spring plus three summer corings (0.64-cm-diam. tines), and a noncored control. At the end of the second year, spring-only and spring-plus-summer cored plots had developed a 66 and 89%, respectively, thicker thatch-mat layer compared with noncored bentgrass. The total organic matter content (weight loss-on-ignition) in thatch- mat layers, however, generally was similar among all three regimes in both years. This indicated that the organic matter was diluted by inclusion of sand from topdressing or reincorporation of cores. Thus, organic matter concentration (i.e., gravimetric organic: dry weight of the cores) in the thatch-mat layer was much lower in plots of both coring regimes vs. noncored plots. Both spring-only and especially spring-plus-summer coring caused substantial reductions in turf quality for a 2-wk period. Spring-plus-summer coring resulted in increased chlorophyll levels as well as improved turf color and quality in late summer. [ABSTRACT FROM AUTHOR]

Examines the usability of bio-organic nitrogen on suppressing turfgrass diseases. Effect of nitrogen on thatch and soil organic matter level; Correlation between dollar spot and soil microbial activity; Comparison on the effectivity between synthetic and non-synthetic sources of nitrogen.